I have lived this nightmare three times in my life. The first time, it was a hard drive that I had accidentally plugged in to a wall socket that was tied to a light switch. People came in and out of the room, turning off the light and rebooting the hard drive without knowing it. It was 120GB. Lost.
Second time, it was an external that just fell off a desk. I cried. 1 terabyte (about 1024GB). Lost.
Third time, another external hard drive died for no apparent reason. It'd just reached the end of its life.
At this point, I had learned my lesson. All. Hard drives. Die. It has nothing to do with how careful you may be, or how safe the drive is, or how expensive or cheap your drive is. These drives are mechanical, and do eventually die. It's important to keep in mind that any and ALL data on this drive WILL eventually be lost. Think about it that way. Whether it's on the internal drive of your computer, or on the external, it WILL get lost.
UNLESS...
You keep a copy.
Making copies is tedious, and even software that does it automatically isn't 100%. It also means you have to purchase a second drive just to hold the copy. I personally don't like doing this, but if you're fine with it, you can stop reading this post.
My solution goes as follows:
The first, easiest, and most important storage solution everyone must have is some basic cloud storage.
Store your documents and anything important on Google Drive, Dropbox, Skydrive, wherever. If you're smart, you'll pay the $5/mo to increase your Google drive storage to 100GB. Move your photo library onto the Google Drive folder, as well as your documents folder on the computer. Always save stuff to this folder, always work off the folder. The day your internal hard drive dies (and trust me, it WILL), you will still have all your stuff safe and sound in Google Drive.
For most people, this will suffice.
For those of you who have large libraries of massive stuff (sound libraries, HD video footage, etc.), you will need to invest in some kind of big fat RAID box. I use a Drobo Mini. It takes four hard drives. It's great. After buying a few terabyte hard drives to fill it, you'll end up spending about $800, but these advanced gizmos have self file-copying technologies, so when one drive dies (and it WILL), you won't actually lose any data. You just need to go out and buy another drive to replace the dead one, and it'll be back up and running, with all your files intact. This is AWESOME.
Anyone with irreplaceable files that you never want to lose (photos, videos of your family, songs you've recorded, any files you're getting paid to work with, etc.) should at LEAST have a basic paid Google Drive account (or similar).
Just remember. All the hard drives in your home/office. (Internal, external, etc.)
WILL
EVENTUALLY
DIE.
